Tic disorders and Tourette syndrome

Clinical picture (children and adolescents)

• Prevalence of Tourette syndrome was 0.52% in a meta-analysis of 21 population studies (Scharf et al., 2015); transient tics are much more common. Compared with national diagnosis data, this suggests that about half of affected children may never have been diagnosed. A
• Tics usually begin at ages 4–6, are most severe in early adolescence and decrease toward adulthood in most children. B
• Premonitory urge: an uncomfortable bodily sensation before a tic that is relieved by the tic. B
• Common co-occurring conditions: ADHD and OCD. A

Circuits and networks

• Putamen and Caudate Nucleus: sensorimotor and habit loops; children with a smaller caudate had more severe tic and OCD symptoms in adulthood (Bloch et al., 2005; 43 children). B
• Premotor Cortex & SMA (including the supplementary motor area) and Primary Motor Cortex: preparing and executing tics. B
• Insula and Anterior Cingulate Cortex: the premonitory urge; a network that activates before the tic (Bohlhalter et al., 2006; 10 adults). C
• Thalamus (centromedian-parafascicular complex) and Globus Pallidus, Internal Segment: deep brain stimulation targets in resistant cases. C
• Cerebellum: active at the moment a tic begins. C

Neurotransmitter systems

• Dopamine (dopamine): dopamine blockers reduce tics; hypothesis of differences in striatal dopamine function. B
• Noradrenaline (noradrenaline): α2 agonists (guanfacine, clonidine) are used especially with co-occurring ADHD. B

Imaging and neurobiological findings

• Inverse relationship between childhood caudate volume and adult symptom severity (Bloch et al., 2005); small sample, not a tool for individual prediction. B

Developmental course

• Tics wax and wane; they increase with stress, fatigue and excitement. In most children they decrease markedly by the end of adolescence. B

Treatment and the systems it targets

• Comprehensive Behavioral Intervention for Tics (CBIT): in 126 children (ages 9–17), clear improvement was 52.5% with CBIT versus about 18.5% with supportive therapy (Piacentini et al., 2010). Tic awareness and competing-response training. A
• Medication: aripiprazole is FDA-approved for Tourette syndrome at ages 6–18; α2 agonists and other antipsychotics are also used. A
• In severe, resistant adult cases, deep brain stimulation (thalamic CM-Pf or GPi); evidence rests on small studies. C

Link to the book (The Green Walnut on the Couch)

• In the book (translated from the Turkish original):
  • Basal ganglia, clinical: "OCD, tics, defenses that have become habits"; where it appears in the book: "tics and premonitory urges (Chapter 9)".
  • Cerebellum, clinical: "OCD, tics, defenses that have become habits".

In the atlas

Regions

Core structures in bold.

Networks

Neurotransmitter pathways

Panksepp systems

References

1. Bloch MH et al. (2005). Caudate volumes in childhood predict symptom severity in adults with Tourette syndrome. Neurology, 65(8), 1253–1258. Search PubMed
2. Bohlhalter S et al. (2006). Neural correlates of tic generation in Tourette syndrome: an event-related functional MRI study. Brain, 129(8), 2029–2037. Search PubMed
3. Piacentini J et al. (2010). Behavior therapy for children with Tourette disorder: a randomized controlled trial. JAMA, 303(19), 1929–1937. Search PubMed
4. Scharf JM et al. (2015). Population prevalence of Tourette syndrome: a systematic review and meta-analysis. Movement Disorders, 30(2), 221–228. Search PubMed